Quadrilateral Sides Proportional Section

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Discussion Overview

The discussion revolves around the properties of a quadrilateral and specific lines drawn within it, particularly focusing on a defined ratio of distances between segments created by these lines. The scope includes theoretical definitions, geometric properties, and potential theorems related to quadrilaterals.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant introduces a concept of a "Sweeping Line," defined as a line that intersects opposite sides of a quadrilateral such that the ratio of the lengths of the sides is maintained.
  • A theorem is presented claiming that there exists only one parabola that is tangent to all Sweeping Lines of a quadrilateral, although this claim is met with skepticism.
  • Another participant suggests that extending the sides of the quadrilateral to meet at a point creates a sweeping line, challenging the idea that a parabola can be tangent to all such lines.
  • Discussion includes the definition of a sweeping line being edited to clarify that it involves intersection rather than bisection of the sides of the quadrilateral.
  • One participant argues that a line connecting midpoints of two sides does not necessarily intersect at the same point as the extended sides of the quadrilateral, yet still qualifies as a sweeping line under the defined ratio.

Areas of Agreement / Disagreement

Participants express differing views on the properties of sweeping lines and the validity of the proposed theorem regarding the parabola. There is no consensus on the claims made, and multiple competing perspectives are present.

Contextual Notes

Definitions and properties discussed may depend on specific geometric configurations and assumptions that are not fully articulated. The implications of the sweeping line concept and its relationship to other geometric theorems remain unresolved.

MilanVlasak
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Sorry guys, I thought it would be easy, but it is not.

I have a random quadrilateral A,B,C,D, drawn and a random point M inside of it.
Now, I want to draw a line passing through the point M and crossing the sides AB and DC at points P and Q.
So far so good, but I want more, in addition the line is required to be constrained by this ratio of distances:

AB:DC=AP:DQ
 
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I got some progress here...

Definition:
If any line bisects the oppozite sides of a Qudrilateral A, B, C, D in points P and Q in such a manner the ratio AB:DC=AP:DQ holds than this line is called a Sweeping Line.

Theorem by Milan Anthony Vlasak:

"There is only one Parabola which is tangent to all Sweeping Lines of a Quadrilateral."

Any objection to that ?
You guys are mathematitions, I am a surveyor.

Milan
 
I can now EDIT the Definition:

Edited Definition:
If any line INTERSECTS the oppozite sides of a Qudrilateral A, B, C, D in points P and Q in such a manner the ratio AB:DC=AP:DQ holds than this line is called a Sweeping Line.
 
If you extend AD and BC until they meet at point R, then RM is a sweeping line.

I don't think any parabola could be tangent to all sweeping lines of a quadrilateral.
 
Last edited:
Orthodontist,

If a line connects the midpoint of AB and the midpoint of CD than extention of this line will not generally pass the intersection point R of AD and BC.

Such midpoint-midpoint line is still a sweeping line according to my definition of a sweeping line: AB:DC=AP:DQ

(Nothing to do with collineation, cross ratio and Papus theorem)

Milan
 
Last edited:

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